1. Field of the Invention
This invention relates to lubricants for synthetic fibers such as mono- and multi-filament polyester and nylon yarn and particularly to lubricants having improved resistance to oxidation at elevated temperatures of at least over 200.degree. C.
2. Description of the Prior Art
Yarns produced from synthetic thermoplastic fibers such as polyesters and polyamides require mechanical and heat treatment to produce the so-called "bulky" yarns, false twist or textured yarns. Since the thermo-mechanical treatment required is of necessity performed as the yarn is travelling at high speed, such processes are facilitated by the application to the yarn, prior to processing, of a lubricating composition. Besides imparting lubricity to the yarn, the lubricant often provides desirable antistatic properties, and emulsification properties. Upon the conclusion of the thermo-mechanical treatment of the yarn, the lubricant should be easily removed by scouring.
In the thermo-mechanical treatment of the yarn, temperatures in the range of 180.degree. to 250.degree. C are often encountered. Therefore, the lubricating agent must be resistant to oxidative degradation and must not volatilize to a substantial degree during such processing. Conventional lubricants for synthetic thermoplastic textile fibers generally suffer from a lack of resistance to oxidation as indicated by the fact that such lubricants exhibit excessive fuming when exposed to temperatures of at least above 200.degree. C and often tar-like, resinous materials derived from such lubricant accumulate on heated plates, utilized in the thermo-mechanical treatment of the yarn, which come in contact with the yarn during such processing.
Since thermo-mechanically treated fiber is often stored over prolonged periods of time prior to the removal of fiber lubricants, not only must the lubricant be oxidation stable but, in addition, must resist discoloration upon exposure to oxides of nitrogen often present in the air especially in industrial locations.
While various antioxidants have been added to polyoxyalkylene compounds utilized as fiber lubricants to protect these compounds against oxidative degradation at elevated temperatures, such antioxidants are generally susceptible to discoloration upon exposure to oxides of nitrogen and thus many such compounds are not useful as components of fiber lubricants.
Antioxidants for polyoxyalkylene compounds are disclosed in U.S. Pat. No. 3,146,272 wherein there is disclosed the use of various monofunctional phenolic compounds as initiators in the production of polyoxyalkylene compounds. These compounds are then utilized in admixture with other polyoxyalkylene compounds susceptible to oxidative deterioration. Compounds such as phenothiazine, phenol and alkylated phenols are disclosed. A bisphenol A bis(propylene glycol) ether dilaurate is disclosed as a component of a stabilized lubricant for nylon and polyester fibers in Japanese 76-70,397. The use of a difunctional phenol such as resorcinol as an initiator in the preparation of polyoxypropylene surfactants is disclosed in U.S. Pat. Nos. 2,674,619 and 3,036,118; the use of aromatic substituted alkylene oxides as initiators in the production of polyoxyalkylene polymers is disclosed in U.S. Pat. No. 2,677,700 and the use of terminal di-vic-epoxides in the production of linear thermoplastic polyether resins based upon bisphenols is shown in U.S. Pat. No. 3,637,590. Such resins are characterized by high impact resistance suitable for use where polycarbonates have been used in the past. Epoxy alkane reactants having terminal epoxide groups are disclosed in U.S. Pat. No. 3,240,819 as useful in the preparation of surfactant compositions by reaction with ethylene glycol. Alpha-olefin epoxides are also disclosed in U.S. Pat. No. 3,475,499 for use as reactants with water or a glycol to produce biodegradable detergents.
In none of these references are the oxidation stable fiber lubricants of this invention disclosed or suggested. Accordingly, it is an object of the invention to provide to the art oxidation stable polyoxyalkylene compounds which are not discolored by exposure to an atmosphere containing oxides of nitrogen and are useful as lubricants for synthetic thermoplastic fibers such as polyester and nylon fibers.